Western Europe vs. Pacific Northwest (temperatures, thunderstorm, comparison, months)

[Botev1912]

Originally Posted by Joe90

Yes that includes trace. I was just trying to show the Paris and the UK, have as many or more days of precipitation than Seattle. The US has a lower threshold for a rainy day (0.25 mm vs 1mm) and given that Seattle is sunnier than either, it would be hard to conclude that Paris is very dry compared to Seattle.

I didn't know Europe used 1 mm threshold. That explains why many places in Europe look drier on paper.

[nei]

Originally Posted by Joe90

Yes that includes trace. I was just trying to show the Paris and the UK, have as many or more days of precipitation than Seattle. The US has a lower threshold for a rainy day (0.25 mm vs 1mm) and given that Seattle is sunnier than either, it would be hard to conclude that Paris is very dry compared to Seattle.

I haven't seen one consistent or official rainfall threshold for the US. Here's Seattle at various thresholds:

SEATTLE TACOMA INTL AP, WASHINGTON Period of Record General Climate Summary - Precipitation

By totals, of course Seattle is obviously wetter and likely by hours as well [difference might be higher since Seattle doesn't get much warm rain].

[Botev1912]

The threshold is 0.01" indeed. Look at the official web site http://www.weather.gov/

[Joe90]

Originally Posted by Botev1912

The threshold is 0.01" indeed. Look at the official web site National Weather Service

0.01nches/0.25mm is misleading though as it is only condensation. All the 0.25mm days I looked at for here, featured largish diurnal range, high air pressure and good visibility and -typical conditions for heavy dew.

Looking at Nei's chart for Seattle, shows the Seattle gets as many rain days as here during summer, if we used the 0.01 in/2.5mm threshold -it's rainier in Seattle during summer, than I thought.

The days that get under the 2.5mm mark during summer here, are typically just heat showers which are very localised. What is the typical rainy summer day in Seattle like?

[Botev1912]

0.01 inches = 0.25 mm, not 2.5

[Joe90]

Originally Posted by Botev1912

0.01 inches = 0.25 mm, not 2.5

Yep. I meant 0.10 inches in that second paragraph. Seattle gets the same number of 0.10 inch/2.5mm days as here in summer, so is a bit rainier than I thought.

Totals under 2.5mm here in summer, are typically just showers from convection -is that the case for Seattle, or does it get more frontal rain in summer, even for small amounts?

[Botev1912]

It usually rains after very hot days, when cooler air arrives (marine layer). There are 2 unstable days and it gets back to warm. This is usually how the west coast gets rain in the warm months. I was in LA once in June and it started raining and it was cool (19C). It almost never rains when it is 22C+.

[nei]

Seattle's summer rain from I remember are cool and drizzly spells, unsure if the Synoptics qualify as frontal. Amounts are typically low except maybe in early June, but it's same type as out of summer rain but not really from any big storms. The weather hour graphs I made showed there weren't any intense summer rain.

With the recent warm summers there I've read a mention of convection but that's not common

Yea, to get really low rainfall days you need to go south to at least Portland.

[nei]

Originally Posted by Botev1912

It usually rains after very hot days, when cooler air arrives (marine layer). There are 2 unstable days and it gets back to warm. This is usually how the west coast gets rain in the warm months. I was in LA once in June and it started raining and it was cool (19C). It almost never rains when it is 22C+.

Interesting didn't realize that was the pattern. Did experience some rain there that didn't fit it

[dunno what to put here]

A lot of our rain in summer comes from showers. It doesn't need to be hot for convection to occur. We had one day last August when the max temp was 26C and we had a few thunderstorms. Had 35mm. Total that month was 91mm.